For Akoya pearls, we use cultured pearl value factor standards provided by Gemological Institute of America (GIA) and The Guide for Grading Akoya Cultured Pearls by Gemworld International, Inc. We use G.I.A. Gem Pearl Master Comparison Set to actually compare with the pearls we grade. The G.I.A. Gem Pearl Master Comparison Set is developed by Gemworld International, Inc. and International Cultured Pearls of The Orient, Inc. for G.I.A. and exclusively provided by G.I.A.